A low-dropout regulator (LDO) is a DC linear voltage regulator that can regulate the output voltage even when the supply voltage is very close to the output voltage. Existing LDOs typically need a reference voltage, a biasing current a high quiescent current for its normal operation. Such LDOs do not work in conditions where there is no external reference voltage, no biasing current and very low quiescent power requirement. The advantages of a low dropout voltage regulator over other DC to DC regulators include the absence of switching noise (as no switching takes place), smaller device size (as neither large inductors nor transformers are needed), and greater design simplicity (usually consists of a reference, an amplifier, and a pass element).